The water supplied to U.S. communities is potentially vulnerable to terrorist attacks by insertion of biological agents. The possibility of such attacks is now of considerable concern. Biological agents could be a threat if they were inserted at critical points in a water supply system; theoretically, they could cause a large number of casualties.
History repeats itself. Deliberate chemical biological contamination of water supplies has been a common occurrence throughout history. Attacks have ranged from the crude dumping of human and animal cadavers into water supplies to well orchestrated contamination with anthrax and cholera. Cyanide has been used as a deadly waterborne poison for thousands of years. In ancient Rome, Nero eliminated his enemies with cherry laurel water (cyanide is the chief toxic ingredient). In the U.S. Civil War, Confederate soldiers shot and left farm animals to rot in ponds during General Sherman's march, compromising the Union water supply. During World War II, the Japanese attacked at least 11 Chinese cities, intending to contaminate food and water supplies with anthrax, cholera, and various other bacteria. Hitler's forces also released sewage into a Bohemia reservoir, deliberately sickening the rival population.
Terrorists are still using chemical or biological weapons (CW/BW). The Aum Shinrikyo Cult attacked a Tokyo subway with sarin gas in 1995 and they are known to have produced and unsuccessfully attempted to use anthrax and botulism toxin nine times as well. In 1985 the Rajneesh religious cult sickened 750 people in The Dalles, Oreg., by spreading salmonella bacteria on local salad bars. In an unprecedented violation of the Geneva Conventions, Yugoslav federal forces, or those allied with them, appear to have poisoned wells throughout Kosovo in October/November 1998. Those responsible dumped animal carcasses and hazardous materials (chemicals like paints, oil, and gasoline) into seventy percent of area wells, deliberately sickening the populace and denying them the use of the wells. Since the horrific events of Sep. 11, 2001, Anthrax again surfaced as a threat when a nameless, faceless terrorist used the U.S. Postal Service to deliver biological weapons in the form of letters to senior Government officials and the press.
Despite a history of armies poisoning rival water supplies, institutional dogma has generally downplayed the risk of asymmetric chemical and biological attacks on water. Nationally recognized as critical infrastructures, water systems are vulnerable to disabling attacks. At present, most governments and their relevant agencies lack comprehensive or robust remediation and counter terrorism processes to address this great potential threat.
The nation's water infrastructure is impossible to fully secure. The sheer vastness of the system with its “raw water” reservoirs and tens of thousands of miles of exposed aqueducts and pipeline with little or minimal security, make it logically and fiscally impossible to completely police. The nation's water system is a delicate balance of interlocking components that includes: the water supply system (dams, reservoirs, wells, etc.); water treatment system; and the water distribution system (pipes, pumps storage tanks, etc.). These systems are mostly aging and in urgent need of upgrading, not simply to bolster them from terrorist attack but to keep them adequately handling the growing water needs of the 21st Century.
Raw water is generally treated at the treatment plant to meet federal, state standards, or Department of Defense (for overseas fixed installations) guidelines and to improve its taste and corrosion characteristics. To meet standards, contaminants must be removed or neutralized. Treatment requirements vary greatly depending on raw water quality and community population (these factors affect which standards apply). A small system supplied by a secure well might only require simple chlorination. Larger systems with surface sources have multiple filtration, physical/chemical modification and disinfection units. Common in the U.S., but typically not used in Europe, chlorine disinfectant is added to kill microbial contamination and residual chlorine is maintained to control microbial life within the system. Examples of other chemical addition are precipitation of iron or other metals, reduction of the water's corrositivity and adding fluoride for children. Upon treatment, the water is considered potable or safe to drink.
By its very nature a treatment plant provides both security from and facilitates chemical or biological attack. Treatment processes may very well remove/neutralize an agent introduced into the raw water or local system. On the other hand, it is the controlling point for system quality where chemicals are deliberately and systematically added to the water. The plant lends itself as an ideal attack point for water downstream in the system. Therefore, treatment plants are potential critical points of a water distribution system.
Two particular points in the water system are also of particular vulnerability and could provide harmful effectiveness to terrorists; water intakes and water distribution:
Water intakes: The potential for contamination increases as water dilution decreases, and such is the case for water intakes. There are 6,800 public supply drinking water intakes on rivers alone in the U.S. Likewise; intakes at the mouths of reservoirs or lakes are also vulnerable targets. Contaminates introduced at the intakes have a far better chance of reaching the population than if introduced elsewhere.
Water distribution: This component of the water supply is the most vulnerable. Pipelines wander for thousands of unprotected miles; aqueducts snake through largely unpopulated areas. A person with a crude knowledge of hydraulics and a bicycle tire pump and access to a kitchen faucet could introduce toxins into any local water distribution system, thus endangering thousands. There are few robust security methods in place to protect these distribution systems.
The distribution system is an underground network of iron, concrete or PVC (plastic) pipes that transport the treated water under pressure to the consumers. Ultimately, water is plumbed into each building from these underground mains. High pressure makes it difficult, though not impossible, to inject material into the typically buried lines. A distribution system typically has a variety of valve pits and other control points where maintenance personnel, or an adversary, may gain access to the water.
Though relatively secure, the system pipes and valves are critical points. Any adversary with access to basic chemical, petrochemical, pharmaceutical, biotechnological or related industry can produce biological or chemical (e.g., “biochem”) weapons into water supply systems. Compared to aerial attack (inhalation or skin contact), effective doses are easier to obtain in water (less dilution than air and directly ingested by the target), and in many cases the materials are more stable (protected from ultraviolet and temperature extremes, although exposed to chlorine). To effectively kill or disable from drinking water chemical and biological agents must be:
1.—Weaponized, meaning it can be produced and disseminated in large enough quantities to cause desired effect.
2.—A viable water threat, meaning it is infectious or toxic from drinking water.
3.—Stable, meaning the agent maintains its structural and virulent effects in water.
4.—Chlorine resistant, meaning the agent isn't significantly oxidized by free available chlorine (FAC) present in most American water systems. Chlorine susceptibility can be negated by inactivation of system chlorination devices.
There are two types of biological threats, pathogens and toxins. Pathogens are live organisms, such as bacteria, viruses or protozoa, which infect and cause illness and/or death. The other are: biological toxins, chemicals derived from organisms, primarily bacteria and fungi, which cause chemical toxicity resulting in illness and/or death. It is believed that for less than $10,000, anyone with gear no more sophisticated than a home brewing kit, protein cultures and personal protection can cultivate trillions of bacteria with relatively little personal risk.
Mankind wages a constant battle against pathogens. Bacteria, viruses, protozoa, nematodes fungi, and others are the causes of most infectious diseases. Living organisms, they require a host population and certain environmental conditions (temperature, humidity/water, and protection from sunlight) for survival. Upon infection, the pathogen must “grow” in the host. This latency period requires time, depending on the organism, from hours to weeks.
The medical profession, and in particular the dental industry and the medical research community, are taking steps to improve the quality of water used in patient care. Dental unit waterlines (the tubes that connect the high-speed handpiece, air/water syringe and ultrasonic scaler to the water supply) have been shown to harbor a wide variety of microorganisms including bacteria, fungi, and protozoans. These microorganisms colonize and replicate on the interior surfaces of the waterline tubing, inevitably resulting in adherent heterogeneous microbial accumulations termed “biofilms.” Biofilms, once formed, serve as a reservoir significantly amplifying the numbers of free-floating microorganisms in water exiting the waterlines. Dental unit water systems currently designed for general dental practice are incapable of efficiently and/or effectively delivering water of an optimal microbiologic quality.
A discussion by Clinical Research Associates (CRA) in its March 1997 newsletter best defines the problem with respect to waterline contamination in the dental field. Water may arrive at a building relatively microbe-free, at about 2 cfu/ml, because of the large diameter water delivery piping. As water lines narrow within the building (within inches in diameter) the microbe count increases to about 10 cfu/ml. At a junction box within the dental unit (with tubing rated at less than an inch in diameter) the count is about 10,000 cfu/ml. After water has traveled about 10 feet within the dental station to the control center, the count can go up to about 400,000 cfu/ml. Finally, at the sterile handpiece and non-sterile air/water supply (the sources of water into a patient's mouth) the microbe count entering the patient's mouth can be 100,000 to 200,000 cfu/ml.
Chemical approaches to disinfecting dental unit water lines have enjoyed varying success. One approach is the use of iodine to disinfect waterlines. The safety and efficacy of chemical disinfection protocols have not been sufficiently validated in the past; therefore the Council has strongly discouraged dentists from treating their dental unit waterlines chemically. In particular, the Council has warned against the use of glutaraldehyde in treatment-water delivery systems to meet the goals set out in the ADA's Statement on Dental Unit Waterlines. Glutaraldehyde is a recognized health hazard; it is a known dermal, mucosal, respiratory and systemic irritant that, as stated on its labeling, is only intended for use in closed containers. In addition to the potentially serious adverse health effects that may be associated with glutaraldehyde when used in dental unit waterlines, such use will essentially fix or “glue” the biofilm matrix to the surface of the waterline, leaving an ideal environment for microbial re-colonization.
To date, however, there is insufficient data to establish the effectiveness of available water sterilization methods. Many of the described methods do not directly address microorganism buildup that may occur within waterlines throughout the day. It is further desirable that treatment in waterlines occur at a point closest to the “point of use” in order to ensure a higher probability of water treatment system effectiveness.